The present invention relates to the field of dipole antenna elements and especially to the use of such antenna elements in arrays for aerospace applications.
Antennas are required for many aerospace applications, such as in electronically scanned arrays for radar or communication systems on aircraft or satellites, and in tracking, telemetry, or seeker antennas for missiles. The radiating elements used in such applications must conform to the surface of the vehicle carrying the antennas and must be both lightweight and capable of being manufactured relatively inexpensively and accurately using printed circuit technology.
Modern surveillance radars also require wide signal bandwidth for scanning. The pattern beamwidth appropriate for wide angle scanning may also require dual orthogonal senses of polarization. Some commonly-used printed circuit elements for conformal array applications include a microstrip patch, a printed circuit dipole and stripline-fed cavity-backed slots. These elements usually have a narrow bandwidth, typically around three percent (3%), which limits their utility. Other commonly used radiating apertures for antenna arrays consist of metallic rectangular or circular waveguides or cavities. These elements, however, are expensive to manufacture and are prohibitively heavy for airborne applications.